Abnormal cells and acellular organisms are known to selectively absorb certain dyes (photosensitive materials) delivered to a treatment site to a more pronounced extent than surrounding tissue. Once presensitized, abnormal cells or acellular organisms can be destroyed by irradiation with light of an appropriate wavelength corresponding to an absorbing wavelength of the photosensitive material, with minimal damage to surrounding normal tissue. This procedure, which is known as photodynamic therapy (PDT), has been clinically used to treat metastatic breast cancer, bladder cancer, head and neck cancers, and other types of malignant tumors.
U.S. Pat. No. 5,676,959 to Heitz et al., purportedly discloses an ingestible phototoxic insecticidal composition including a photoactive dye, an attractant compound and/or feeding stimulant, and an adjuvant, whereby the adjuvant interacts with the photoactive dye and insect gastrointestinal (GI) tract to facilitate transport of the phototoxic insecticide across the GI tract. The use of an adjuvant to facilitate pharmaceutical uptake via GI tract absorption is known in the art. Unlike the surface acting agents of the Applicant's present invention, these adjuvants do not produce a disorientation of a cell membrane so that the cell membrane no longer functions as an effective osmotic barrier.
The article “Inactivation of Gram-Negative Bacteria by Photosensitized Porphyrins” by Nitzan, et al., published in Photochemistry and Photobiology, Vol. 55, No. 1, pp. 89-96, 1992, purportedly discloses the use of polycationic agent polymyxin nonapeptide (PMNP) in association with a photoactive agent, deuteroporphyin (DP). PMNP is disclosed to disturb the outer membrane of a gram-negative bacteria so as to permit access of the DP to bind to the internal lipoprotein osmotic membrane of the bacterial cell. PMNP is disclosed to only disturb the outer membrane structure and not its function, and not cause metabolic leakage from the cells (or osmotic changes in the cell). Unlike the surface acting agent of the Applicant's present invention, PNMP does not produce a disorientation of a cell membrane so that the cell membrane no longer functions as an effective osmotic barrier. In the Applicant's present invention, the surface acting agent causes a disorientation of the cell membrane thereby compromising the effective osmotic membrane barrier and thus allowing the photosensitizer to diffuse through the compromised cell membrane into the cell.
U.S. Pat. No. 5,616,342, to Lyons, purportedly discloses an emulsion comprising a lipid, a poorly water-soluble photosensitizing compound, a surfactant, and a cosurfactant. Poorly water-soluble photosensitizers are disclosed to pose serious challenges to achieving suitable formulation for administration to the body. Lyons '342 discloses that surfactants facilitate the preparation of the emulsion by stabilizing the dispersed droplets of an oil-in-water emulsion, and that the use of surfactants in combination with poorly water-soluble pharmacologic compounds is known in the art. Unlike the surface acting agents of the Applicant's present invention, the surfactant in Lyons does not produce a disorientation of a cell membrane so that the cell membrane no longer functions as an effective osmotic barrier.